Tumour necrosis factor alpha in fat redistribution syndromes associated with combination antiretroviral therapy in HIV-1-infected patients: potential role in subcutaneous adipocyte apoptosis

Adipose tissue plasticity and the pleiotropic roles of BMP signaling

Adipose tissues, including white, beige, and brown adipose tissue, have evolved to be highly dynamic organs. Adipose tissues undergo profound changes during development and regeneration and readily undergo remodeling to meet the demands of an everchanging metabolic landscape. The dynamics are determined by the high plasticity of adipose tissues, which contain various cell types: adipocytes, immune cells, endothelial cells, nerves, and fibroblasts. There are numerous proteins that participate in regulating the plasticity of adipose tissues. Among these, bone morphogenetic proteins (BMPs) were initially found to regulate the differentiation of adipocytes, and they are being reported to have pleiotropic functions by emerging studies. Here, in the first half of the article, we summarize the plasticity of adipocytes and macrophages, which are two groups of cells targeted by BMP signaling in adipose tissues. We then review how BMPs regulate the differentiation, death, and lipid metabolism of adipocytes. In addition, the potential role of BMPs in regulating adipose tissue macrophages is considered. Finally, the expression of BMPs in adipose tissues and their metabolic relevance are discussed.

JAK/STAT inhibitor therapy partially rescues the lipodystrophic autoimmune phenotype in Clec16a KO mice

CLEC16A is implicated in multiple autoimmune diseases. We generated an inducible whole-body knockout (KO), Clec16a^ΔUBC mice to address the role of CLEC16A loss of function. KO mice exhibited loss of adipose tissue and severe weight loss in response to defective autophagic flux and exaggerated endoplasmic reticulum (ER) stress and robust cytokine storm. KO mice were glucose tolerant and displayed a state of systemic inflammation with elevated antibody levels, including IgM, IgA, Ig2b and IgG3, significantly reduced circulating insulin levels in the presence of normal food consumption. Metabolic analysis revealed disturbances in the lipid profile, white adipose decreasing concomitantly with enhanced inflammatory response, and energy wasting. Mechanistically, endoplasmic reticulum (ER) stress triggers excessive hormone sensitive lipases (HSL) mediated lipolysis which contributes to adipose inflammation via activation of JAK-STAT, stress kinases (ERK1/2, P38, JNK), and release of multiple proinflammatory mediators. Treatment with a JAK-STAT inhibitor (tofacitinib) partially rescued the inflammatory lipodystrophic phenotype and improved survival of Clec16a^ΔUBC mice by silencing cytokine release and modulating ER stress, lipolysis, mitophagy and autophagy. These results establish a mechanistic link between CLEC16A, lipid metabolism and the immune system perturbations. In summary, our Clec16a^ΔUBC mouse model highlights multifaceted roles of Clec16a in normal physiology, including a novel target for weight regulation and mutation-induced pathophysiology.

BMPR2 promotes fatty acid oxidation and protects white adipocytes from cell death in mice

Adipocyte cell death is pathologically involved in both obesity and lipodystrophy. Inflammation and pro-inflammatory cytokines are generally regarded as inducers for adipocyte apoptosis, but whether some innate defects affect their susceptibility to cell death has not been extensively studied. Here, we found bone morphogenetic protein receptor type 2 (BMPR2) knockout adipocytes were prone to cell death, which involved both apoptosis and pyroptosis. BMPR2 deficiency in adipocytes inhibited phosphorylation of perilipin, a lipid-droplet-coating protein, and impaired lipolysis when stimulated by tumor necrosis factor (TNFα), which lead to failure of fatty acid oxidation and oxidative phosphorylation. In addition, impaired lipolysis was associated with mitochondria-mediated apoptosis and pyroptosis as well as elevated inflammation. These results suggest that BMPR2 is important for maintaining the functional integrity of adipocytes and their ability to survive when interacting with inflammatory factors, which may explain why adipocytes among individuals show discrepancy for death responses in inflammatory settings.

Qian, Pan, Su et al. show that bone morphogenetic protein receptor type 2 (BMPR2) deficiency makes white adipocytes prone to death. This study suggests that BMPR2 is required for fat cells to effectively generate energy from the stored fat for their survival during energetically demanding situations such as inflammation.

Sulforaphane induces apoptosis in adipocytes via Akt/p70s6k1/Bad inhibition and ERK activation

Sulforaphane (SFN), an isothiocyanate isolated from cruciferous vegetables, possesses anti-oxidant and anti-cancer bioactivities. Moreover, SFN exerts its pro-apoptotic effects in some cancer lines. However, the effects and mechanisms of SFN on the regulation of apoptosis of adipocytes are still unknown. In this study, we found that SFN induced significant apoptosis in 3T3-L1 adipocytes and markedly decreased the cellular lipid content. Western blot demonstrated that SFN-induced apoptosis was mediated via the mitochondrial apoptosis pathway based on increased cleavage of poly-ADP-ribose-polymerase (PARP), release of cytochrome c into the cytoplasm, and activation of caspase-3, as well as decreased Bcl-2/Bax ratio. In addition, SFN markedly decreased phosphorylation of Akt and downstream proteins, p70s6k1 and Bad, and increased phosphorylation of ERK. Therefore, our findings clarified that SFN could induce 3T3-L1 adipocyte apoptosis via down-regulation of the Akt/p70s6k1/Bad pathway and up-regulation of the ERK pathway, suggesting SFN may be a promising agent for the treatment or prevention of obesity.

Different origin of adipogenic stem cells influences the response to antiretroviral drugs

Lipodystrophy (LD) is a main side effect of antiretroviral therapy for HIV infection, and can be provoked by nucleoside reverse transcriptase inhibitors (NRTIs) and protease inhibitors (PIs). LD exists in different forms, characterized by fat loss, accumulation, or both, but its pathogenesis is still unclear. In particular, few data exist concerning the effects of antiretroviral drugs on adipocyte differentiation. Adipose tissue can arise either from mesenchymal stem cells (MSCs), that include bone marrow-derived MSCs (hBM-MSCs), or from ectodermal stem cells, that include dental pulp stem cells (hDPSCs). To analyze whether the embryonal origin of adipocytes might impact the occurrence of different phenotypes in LD, we quantified the effects of several antiretroviral drugs on the adipogenic differentiation of hBM-MSCs and hDPSCs. hBM-MSCs and hDPSCs were isolated from healthy donors. Cells were treated with 10 and 50 μM stavudine (d4T), efavirenz (EFV), atazanavir (ATV), ritonavir (RTV), and ATV-boosted RTV. Viability and adipogenesis were evaluated by staining with propidium iodide, oil red, and adipoRed; mRNA levels of genes involved in adipocyte differentiation, i.e. CCAAT/enhancer-binding protein alpha (CEBPα) and peroxisome proliferator-activated receptor gamma (PPARγ), and in adipocyte functions, i.e. fatty acid synthase (FASN), fatty acid binding protein-4 (FABP4), perilipin-1 (PLIN1) and 1-acylglycerol-3-phosphate O-acyltransferase-2 (AGPAT2), were quantified by real time PCR. We found that ATV, RTV, EFV, and ATV-boosted RTV, but not d4T, caused massive cell death in both cell types. EFV and d4T affected the accumulation of lipid droplets and induced changes in mRNA levels of genes involved in adipocyte functions in hBM-MSCs, while RTV and ATV had little effects. All drugs stimulated the accumulation of lipid droplets in hDPSCs. Thus, the adipogenic differentiation of human stem cells can be influenced by antiretroviral drugs, and depends, at least in part, on their embryonal origin.

Viral mechanisms of adipose dysfunction: lessons from HIV-1 Vpr

HIV-associated lipodystrophy is a heterogeneous, evolving condition associated with fundamental defects in adipose tissue differentiation, turnover and function. Although many antiretroviral drugs can affect adipose tissues adversely, clinical evidence suggests that factors associated with the virus per se could play a role. We have focused on the possibility that an HIV accessory protein, viral protein R (Vpr) could dysregulate metabolically critical transcription factors to cause the adipose dysfunction. In a recent study published in Science Translational Medicine, we utilized 2 animal models to show that Vpr, produced in tissues that sequester HIV after antiretroviral therapy, can act in a paracrine or endocrine fashion to disrupt adipocyte differentiation and function by inhibiting PPARγ target gene expression and activating glucocorticoid target gene expression. The phenotypic consequences included many features typical of the human syndrome, including accelerated lipolysis, increased macrophage infiltration in adipose tissue, diminished size of white adipose depots and hepatic steatosis. In this commentary, we summarize the background, results, and implications of these studies, and raise important questions for future investigation. More broadly, these studies suggest that chronic viral infections may be a causative factor in the pathogenesis of some forms of lipid metabolic disease, insulin resistance, and diabetes.

Genetic variation in the promoter region of pro-inflammatory cytokine TNF-α in perinatal HIV transmission from Mumbai, India

Various host factors such as cytokines and HLA, regulate the immune system and influence HIV transmission to infants exposed to HIV-1 through their mothers. Tumor Necrosis Factor Alpha (TNF-α) is a strong pro-inflammatory mediator and thought to influence vulnerability to HIV infection (and/or) transmission. Polymorphisms in regulatory regions are known to govern the production of this cytokine. However, the association of these variations in perinatal HIV transmission is yet to be established. Present study aimed to evaluate if polymorphisms in promoter region of TNF-α gene is associated with perinatal HIV transmission. With informed consent from parents, infants' blood was collected for HIV screening and SNPs analysis at 2 loci: TNF (rs1800629) and TNF (rs361525) using PCR-SSP method. HIV positive (n = 27) and negative (n = 54) children at the end of 18th month follow up were considered for this study. GG genotype, responsible for low expression of TNF (rs1800629) was significantly (p = 0.005) higher in uninfected children, while higher GA genotype frequency was observed in infected children. The 'G' allele frequency was significantly higher in negative children (p = 0.016). We conclude that genotypic variants of TNF (rs1800629) are a likely contributor to perinatal HIV transmission. This provides new insights in markers of differential susceptibility to perinatal HIV transmission.

Changes in subcutaneous adipose tissue microRNA expression in HIV-infected patients

OBJECTIVES

We evaluated the possibility that a pattern of abnormal microRNA (miRNA) expression could be fuelling the mechanisms causing HIV-associated lipodystrophy (HAL).

METHODS

In this case-control study, samples of subcutaneous adipose tissue from eight consecutive HIV-infected patients on combination antiretroviral therapy with HAL (cases) were compared with those of eight HIV-negative subjects (controls). Human miRNA microarrays were used to probe the transcriptomes of the samples. Analysis of differentially expressed miRNAs was performed using DataAssist v2.0 software, applying a paired Student's t-test.

RESULTS

Data showed that 21 miRNAs out of 754 were overexpressed in the patient group. Ten of these (i.e. miR-186, miR-199a-3p, miR-214, miR-374a, miR-487b, miR-532-5p, miR-628-5p, miR-874, miR-125-b-1* and miR-374b*) were up-regulated to a significant degree (fold change >2.5; P < 0.01). Eleven other miRNAs (i.e. miR-let-7d, miR-24, miR-30c, miR-125a-3p, miR-149, miR-191, miR-196-b, miR-218, miR-342-3p, miR-452 and miR-454*) were 2- to 2.5-fold more expressed in HIV+ samples than in controls. Levels of mRNA for lipin 1, the target of miR-218, were significantly lower in subcutaneous adipose tissue from HIV patients.

CONCLUSIONS

In adipocytes of HIV-infected patients, the up-regulation of specific miRNAs could lead to an increased 'activation' that might contribute to the pathogenesis of HAL by increasing cell turnover and/or promotion of apoptosis.

Adipokines, hormones related to body composition, and insulin resistance in HIV fat redistribution syndrome

Background

Lipodystrophies are characterized by adipose tissue redistribution, insulin resistance (IR) and metabolic complications. Adipokines and hormones related to body composition may play an important role linking these alterations. Our aim was to evaluate adipocyte-derived hormones (adiponectin, leptin, resistin, TNF-α, PAI-1) and ghrelin plasma levels and their relationship with IR in HIV-infected patients according to the presence of lipodystrophy and fat redistribution.

Methods

Anthropometric and metabolic parameters, HOMA-IR, body composition by DXA and CT, and adipokines were evaluated in 217 HIV-infected patients on cART and 74 controls. Fat mass ratio defined lipodystrophy (L-FMR) was defined as the ratio of the percentage of the trunk fat mass to the percentage of the lower limb fat mass by DXA. Patient’s fat redistribution was classified into 4 different groups according the presence or absence of either clinical lipoatrophy or abdominal prominence: no lipodystrophy, isolated central fat accumulation (ICFA), isolated lipoatrophy and mixed forms (MXF). The associations between adipokines levels and anthropometric, metabolic and body composition were estimated by Spearman correlation.

Results

Leptin levels were lower in patients with FMR-L and isolated lipoatrophy, and higher in those with ICFA and MXF. Positive correlations were found between leptin and body fat (total, trunk, leg, arm fat evaluated by DXA, and total, visceral (VAT), subcutaneous adipose tissue (SAT), and VAT/SAT ratio evaluated by CT) regardless of FMR-L, and with HOMA-IR only in patients with FMR-L. Adiponectin correlated negatively with VAT, and its mean levels were lower in patients with ICFA and higher in those with no lipodystrophy. Resistin was not correlated with adipose tissue but positively correlated with HOMA-IR in FMR-L patients. PAI-1 levels were higher in MXF-patients and their levels were positively correlated with VAT in those with FMR-L. Ghrelin was higher in HIV-infected patients than controls despite BMI-matching.

Conclusion

The overall body fat reduction in HIV lipoatrophy was associated with low leptin plasma levels, and visceral fat accumulation was mainly associated with decreased plasma levels of adiponectin.

Nutrition and the HIV-associated lipodystrophy syndrome. Nutr Res Rev. 2012;25:267-287. [PMID: 23174511 DOI: 10.1017/s0954422411000138]

HIV-associated lipodystrophy syndrome (HALS), comprising metabolic and morphological alterations, is a known side effect of highly active antiretroviral therapy (HAART). Evidence for the role of nutrition in the management of the systemic parameters of HALS is currently limited. In the present paper we review the current knowledge base surrounding HALS, focusing particularly on the role of nutrition in mitigating the systemic parameters of the syndrome. Reported prevalence of HALS was found to vary from 9 to 83 % due to lack of a standardised definition, as well as variations in assessment methods and in the study population used. HALS is associated with both morphological (lipoatrophy, lipohypertrophy) and metabolic (dyslipidaemia, glucose intolerance, diabetes, hypertension, endothelial dysfunction and atherosclerosis) alterations, which may occur singly or in combination, and are associated with an increased risk of CVD. HAART-induced adipocyte inflammation, oxidative stress and macrophage infiltration, as well as altered adipocyte function and mitochondrial toxicity, have been shown to be central to the development of HALS. The adipocyte, therefore, represents a plausible target for treatment. Pharmacological and surgical treatment interventions have shown effect. However, their use is associated with numerous adverse effects and complications. Targeted lifestyle interventions may provide a useful alternative for managing HALS owing to their safety and tolerability. A Mediterranean-style diet has been found to be effective in improving the systemic parameters of HALS. Furthermore, the effects of n-3 PUFA supplementation are encouraging and future randomised controlled trials investigating the beneficial effects of n-3 PUFA in HALS are justified.

Adipogenic/lipid, inflammatory, and mitochondrial parameters in subcutaneous adipose tissue of untreated HIV-1-infected long-term nonprogressors: significant alterations despite low viral burden

BACKGROUND

HIV-1 can induce disturbances in adipose tissue in infected subjects through the effects of some of its proteins or inflammation. It is not known whether this also takes place in HIV-1-infected long-term nonprogressors (LTNPs). Our objectives were to determine whether adipocyte differentiation/lipid, inflammatory, and mitochondrial parameters are perturbed in abdominal wall subcutaneous adipose tissue of untreated HIV-1-infected patients LTNPs.

METHODS

Cross-sectional study involving 10 LTNPs, 10 typical progressors (TPs), and 10 uninfected controls (UCs). The parameters assessed were peroxisome proliferator-activated receptor-gamma (PPARγ), lipoprotein lipase, and fatty acid-binding protein 4 mRNA (adipogenic/lipid); tumor necrosis factor-alpha, interleukin 18 (IL-18), β2-MCG, monocyte chemoattractant protein 1, CD1A, and C3 mRNA (inflammation); and cytochrome c oxidase subunit II (COII), COIV, CYCA, nuclear respiratory factor 1, PPARγ coactivator 1α mRNA, and mtDNA content (mitochondrial).

RESULTS

Regarding adipogenic/lipid parameters, LTNPs had PPARγ, lipoprotein lipase, and fatty acid-binding protein 4 mRNA significantly decreased compared with UCs (P ≤ 0.001 for all comparisons). PPARγ mRNA was significantly greater in LTNP than in TP (P = 0.006). With respect to inflammatory parameters, tumor necrosis factor-alpha, IL-18, and β2-MCG mRNA were significantly higher in LTNPs compared with UCs (P < 0.005 for all comparisons), whereas IL-18 mRNA was greater in TPs compared with LTNPs (P = 0.01). As mitochondrial parameters are concerned, mtDNA was significantly reduced in LTNPs compared with TPs (P = 0.04) and UCs (P = 0.03). COII and COIV were also significantly reduced in LTNPs compared with UCs and TPs.

CONCLUSIONS

Adipose tissue from untreated LTNPs may have limited but significant derangements in some adipogenic/lipid and may have inflammatory processes at a lower degree than that observed in untreated TPs. LTNPs may have mitochondrial-related alterations in adipose tissue which are greater than that observed in TPs.

Pharmacogenetics of the lipodystrophy syndrome associated with HIV infection and combination antiretroviral therapy

INTRODUCTION

Antiretroviral drugs have been associated with several toxicities that limit their success. Of the chronic toxicities, the lipodystrophy syndrome is of special concern due to the metabolic alterations that can accompany it. Why some patients treated with a particular antiretroviral regimen develop lipodystrophy, while others do not, is a medical mystery, but it has been suggested that individuals may (or may not) have a genetically conditioned predisposition. Pharmacogenetics is the science that studies how the genetic composition of individuals can give rise to interindividual variations in response to drugs and drug toxicity.

AREAS COVERED

This article reviews the published investigations on the association between host genetic determinants in treated HIV-infected patients and the presence of lipodystrophy. Studies were identified through a PubMed database search. Case-control and longitudinal studies into pharmacogenetic association were selected. Areas covered include the data on the genetic variants of mitochondrial parameters, cytokines, adipokines, proteins involved in adipocyte biology and proteins involved in stavudine metabolism.

EXPERT OPINION

Most studies provide inconsistent data due to partial genetic evaluation, different assessment of lipodystrophy and low number of patients evaluated. The pharmacogenetics of lipodystrophy in HIV-infected patients treated with antiretroviral drugs still belongs in the research laboratory.

Plasmodium inui infection reduces the efficacy of a simian immunodeficiency virus DNA vaccine in a rhesus macaque model through alteration of the vaccine-induced immune response

Human immunodeficiency virus type 1 and malaria are co-endemic in many areas. We evaluated the effects of Plasmodium inui infection on the performance of a simian immunodeficiency virus (SIV) DNA vaccine. Rhesus macaques were infected with P. inui by transfusion of whole blood from a persistently infected animal. Animals with and animals without P. inui infection were then vaccinated 4 times with an SIV DNA vaccine encoding SIVgag, SIVpol, and SIVenv. Animals were subsequently challenged with thirty 50% rhesus monkey infectious doses of SIVmac251 6 weeks after the last vaccination. P. inui-infected immunized animals showed a significantly higher viral load than animals without P. inui infection (P = .010, by the Wilcoxon rank sum test). The higher viral loads in the P. inui-infected animals were durable and were observed at all sampling time points across the study (P = .00245, by the Wilcoxon rank test). The P. inui-infected animals also had correspondingly lower CD4(+) cell counts. There were fewer vaccine-specific CD4(+) and CD8(+) cells in the P. inui-infected animals, compared with uninfected animals. Of importance, P. inui infection seemed to decrease the number of CD8(+) cells that could proliferate or secrete interferon γ, although the number of CD8(+) cells capable of secreting tumor necrosis factor α following in vitro stimulation was increased. This study demonstrated that P. inui infection had an influence on the immune response to an SIV DNA vaccine and decreased the vaccine's efficacy.

The deleterious influence of tenofovir-based therapies on the progression of atherosclerosis in HIV-infected patients

We investigated the potential differential effects of antiretroviral therapies on unbalanced chemokine homeostasis and on the progression of atherosclerosis in HIV-infected patients. A two-year prospective study was performed in 67 consecutive HIV-infected patients initiating antiretroviral therapy with abacavir/lamivudine or tenofovir/emtricitabine. Circulating levels of inflammatory biomarkers, progression of subclinical atherosclerosis and expression levels of selected chemokines genes in circulating leukocytes were assessed. Control subjects showed significantly lower plasma concentrations of CRP, tPA, IL-6, and MCP-1 than HIV-infected patients at a baseline. After two years of followup, the observed decreases in plasma inflammatory biomarker levels were only significant for MCP-1, tPA, and IL-6. The decrease in plasma MCP-1 concentration was associated with the progression of atherosclerosis, and this effect was negligible only in patients receiving TDF-based therapy. Multivariate analysis confirmed that treatment with TDF was positively and significantly associated with a higher likelihood of subclinical atherosclerosis progression. However, the expression levels of selected genes in blood cells only showed associations with the viral load and total and HDL-cholesterol levels. Current antiretroviral treatments may partially attenuate the influence of HIV infection on certain inflammatory pathways, though patients receiving TDF therapy must be carefully monitored with respect to the presence and/or progression of atherosclerosis.

Adipose tissue biology and HIV-infection

HIV-1/highly active antiretroviral therapy-associated lipodystrophy syndrome (HALS) is an adipose tissue redistribution disorder characterized by subcutaneous adipose tissue lipoatrophy, sometimes including visceral adipose tissue hypertrophy and accumulation of dorsocervical fat ('buffalo hump'). The pathophysiology of HALS appears to be multifactorial and several key pathophysiological factors associated with HALS have been identified. These include mitochondrial dysfunction, adipocyte differentiation disturbances, high adipocyte lipolysis, and adipocyte apoptosis. These alterations in adipose tissue biology expand to involve systemic metabolism through alterations in endocrine functions of adipose tissue (via disturbed adipokine release), enhanced production of pro-inflammatory cytokines and excessive free fatty-acid release due to lipolysis. The deleterious action of some antiretroviral drugs is an important factor in eliciting these alterations in adipose tissue. However, HIV-1 infection-related events and HIV-1-encoded proteins also contribute directly to the complex development of HALS through effects on adipocyte biology, or indirectly through the promotion of local inflammation in adipose tissue.

No relationship between TNF-α genetic variants and combination antiretroviral therapy-related lipodystrophy syndrome in HIV type 1-infected patients: a case-control study and a meta-analysis

Tumor necrosis factor alpha (TNF-α) is thought to be involved in the pathogenic and metabolic events associated with HIV-1 infection. We assessed whether carriage of the TNF-α gene promoter single nucleotide polymorphism (SNP) is associated with lipodystrophy and metabolic derangements in HIV-1-infected patients treated with cART. We also assessed variations in TNF-α receptor plasma levels. The study group comprised 286 HIV-1-infected patients (133 with and 153 without lipodystrophy) and 203 uninfected controls (UC). TNF-α -238G > A, -308G > A, and -863 C > A SNP were assessed using PCR-RFLPs on white cell DNA. Plasma sTNF-α R1 and R2 levels were measured by ELISA. Student's t test, the χ(2) test, Pearson correlations, and the logistic regression test were performed for statistical analysis. The TNF-α -308G > A SNP was significantly associated with lipodystrophy in the univariate analysis (p = 0.04). This association, however, was no longer significant in the multivariate analysis. A meta-analysis of the published literature and our own data, which included 284 patients with lipodystrophy and 338 without lipodystrophy, showed that there was no relationship between the TNF-α -238G > A and -308G > A SNP and lipodystrophy (p > 0.05 for all comparisons). HIV-1-infected patients had greater sTNF-α R2 plasma levels than UC (p = 0.001) whereas sTNF-α R1 and R2 levels were not significantly different in both the HIV-1-infected cohorts, lipodystrophy vs. nonlipodystrophy (p = NS). In our cohort of white Spaniards the TNF-α -238G > A, -308G > A, and -863C > A SNP were not associated with lipodystrophy in HIV-1-infected patients treated with cART. This finding was replicated in a meta-analysis of the published data, which showed no associations between the TNF-α -238G > A and -308G > A SNP and lipodystrophy. In HIV-1-infected patients under cART there is a systemic overproduction of sTNF-α R2, which is unrelated to the presence of lipodystrophy.

Effect of TNF-alpha genetic variants and CCR5 Delta 32 on the vulnerability to HIV-1 infection and disease progression in Caucasian Spaniards

BACKGROUND

Tumor necrosis factor alpha (TNF-alpha) is thought to be involved in the various immunogenetic events that influence HIV-1 infection.

METHODS

We aimed to determine whether carriage of the TNF-alpha-238G>A, -308G>A and -863 C>A gene promoter single nucleotide polymorphisms (SNP) and the CCR5 Delta 32 variant allele influence the risk of HIV-1 infection and disease progression in Caucasian Spaniards. The study group consisted of 423 individuals. Of these, 239 were uninfected (36 heavily exposed but uninfected [EU] and 203 healthy controls [HC]) and 184 were HIV-1-infected (109 typical progressors [TP] and 75 long-term nonprogressors [LTNP] of over 16 years' duration). TNF-alpha SNP and the CCR5 Delta 32 allele were assessed using PCR-RFLP and automatic sequencing analysis methods on white blood cell DNA. Genotype and allele frequencies were compared using the chi 2 test and the Fisher exact test. Haplotypes were compared by logistic regression analysis.

RESULTS

The distribution of TNF-alpha-238G>A, -308G>A and -863 C>A genetic variants was non-significantly different in HIV-1-infected patients compared with uninfected individuals: -238G>A, p = 0.7 and p = 0.3; -308G>A, p = 0.05 and p = 0.07; -863 C>A, p = 0.7 and p = 0.4, for genotype and allele comparisons, respectively. Haplotype analyses, however, indicated that carriers of the haplotype H3 were significantly more common among uninfected subjects (p = 0.04). Among the infected patients, the distribution of the three TNF-alpha genetic variants assessed was non-significantly different between TP and LTNP: -238G>A, p = 0.35 and p = 0.7; -308G>A, p = 0.7 and p = 0.6: -863 C>A, p = 0.2 and p = 0.2, for genotype and allele comparisons, respectively. Haplotype analyses also indicated non-significant associations. Subanalyses in the LTNP subset indicated that the TNF-alpha-238A variant allele was significantly overrepresented in patients who spontaneously controlled plasma viremia compared with those who had a detectable plasma viral load (genotype comparisons, p = 0.02; allele comparisons, p = 0.03). The CCR5 Delta 32 distribution was non-significantly different in HIV-1-infected patients with respect to the uninfected population (p = 0.15 and p = 0.2 for genotype and allele comparisons, respectively) and in LTNP vs TP (p = 0.4 and p = 0.5 for genotype and allele comparisons, respectively).

CONCLUSIONS

In our cohort of Caucasian Spaniards, TNF-alpha genetic variants could be involved in the vulnerability to HIV-1 infection. TNF-alpha genetic variants were unrelated to disease progression in infected subjects. The -238G>A SNP may modulate the control of viremia in LTNP. Carriage of the CCR5 Delta 32 variant allele had no effect on the risk of infection and disease progression.

Adipocyte dysfunction in response to antiretroviral therapy: clinical, tissue and in-vitro studies

PURPOSE OF REVIEW

Lipodystrophy, a major complication of antiretroviral therapy, is an adipose tissue disease involving severe alterations of fat tissue distribution and metabolic functions. Protease inhibitors and nucleoside reverse transcriptase inhibitors (NRTIs) are implicated to different extents. We review recent findings on the toxicity of HIV antiretroviral drugs at the fat cell and tissue levels and point out the underlying pathophysiological mechanisms.

RECENT FINDINGS

Peripheral fat loss and central accumulation are distinct phenomena. Lipoatrophy is the dominant feature after prolonged treatment. Protease inhibitors and NRTIs promote fat tissue disease by separate mechanisms that converge and worsen adipocyte dysfunctions. The pathogenesis involves the mitochondrial toxicity of NRTIs and the adverse effects of protease inhibitors and NRTIs on adipocyte differentiation status, insulin sensitivity, survival and adipokine secretion. Oxidative stress and local inflammation induced by these drugs may participate in the setup of lipodystrophy. Partial and slow reversion can be obtained by switch strategies or drug therapy.

SUMMARY

Patients using antiviral therapy develop severe fat tissue damage. The toxicity of protease inhibitors and NRTIs remains an important issue for patients and clinicians. Since fat tissue regeneration is difficult, it is important to understand the mechanisms by which these drugs alter fat tissue depots.

Dietary blueberry attenuates whole-body insulin resistance in high fat-fed mice by reducing adipocyte death and its inflammatory sequelae

Adipose tissue (AT) inflammation promotes insulin resistance (IR) and other obesity complications. AT inflammation and IR are associated with oxidative stress, adipocyte death, and the scavenging of dead adipocytes by proinflammatory CD11c+ AT macrophages (ATMPhi). We tested the hypothesis that supplementation of an obesitogenic (high-fat) diet with whole blueberry (BB) powder protects against AT inflammation and IR. Male C57Bl/6j mice were maintained for 8 wk on 1 of 3 diets: low-fat (10% of energy) diet (LFD), high-fat (60% of energy) diet (HFD) or the HFD containing 4% (wt:wt) whole BB powder (1:1 Vaccinium ashei and V. corymbosum) (HFD+B). BB supplementation (2.7% of total energy) did not affect HFD-associated alterations in energy intake, metabolic rate, body weight, or adiposity. We observed an emerging pattern of gene expression in AT of HFD mice indicating a shift toward global upregulation of inflammatory genes (tumor necrosis factor-alpha, interleukin-6, monocyte chemoattractant protein 1, inducible nitric oxide synthase), increased M1-polarized ATMPhi (CD11c+), and increased oxidative stress (reduced glutathione peroxidase 3). This shift was attenuated or nonexistent in HFD+B-fed mice. Furthermore, mice fed the HFD+B were protected from IR and hyperglycemia coincident with reductions in adipocyte death. Salutary effects of BB on adipocyte physiology and ATMPhi gene expression may reflect the ability of BB anthocyanins to alter mitogen-activated protein kinase and nuclear factor-kappaB stress signaling pathways, which regulate cell fate and inflammatory genes. These results suggest that cytoprotective and antiinflammatory actions of dietary BB can provide metabolic benefits to combat obesity-associated pathology.

Fat poetry: a kingdom for PPAR gamma

Adipose tissue is not an inert cell mass contributing only to the storage of fat, but a sophisticated ensemble of cellular components with highly specialized and complex functions. In addition to managing the most important energy reserve of the body, it secretes a multitude of soluble proteins called adipokines, which have beneficial or, alternatively, deleterious effects on the homeostasis of the whole body. The expression of these adipokines is an integrated response to various signals received from many organs, which depends heavily on the integrity and physiological status of the adipose tissue. One of the main regulators of gene expression in fat is the transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), which is a fatty acid- and eicosanoid-dependent nuclear receptor that plays key roles in the development and maintenance of the adipose tissue. Furthermore, synthetic PPARgamma agonists are therapeutic agents used in the treatment of type 2 diabetes.This review discusses recent knowledge on the link between fat physiology and metabolic diseases, and the roles of PPARgamma in this interplay via the regulation of lipid and glucose metabolism. Finally, we assess the putative benefits of targeting this nuclear receptor with still-to-be-identified highly selective PPARgamma modulators.

Antiretroviral-related adipocyte dysfunction and lipodystrophy in HIV-infected patients: Alteration of the PPARγ-dependent pathways

Lipodystrophy and metabolic alterations are major complications of antiretroviral therapy in HIV-infected patients. In vitro studies using cultured murine and human adipocytes revealed that some protease inhibitors (PIs) and nucleoside reverse transcriptase inhibitors (NRTIs) were implicated to a different extent in adipose cell dysfunction and that a chronic incubation with some PIs decreased mRNA and protein expression of PPARγ. Defective lamin A maturation linked to PI inhibitory activity could impede the nuclear translocation of SREBP1c, therefore, reducing PPARγ expression. Adipose cell function was partially restored by the PPARγ agonists, thiazolidinediones. Adverse effects of PIs and NRTIs have also been reported in macrophages, a cell type that coexists with, and modulates, adipocyte function in fat tissue. In HIV-infected patients under ART, a decreased expression of PPARγ and of PPARγ-related genes was observed in adipose tissue, these anomalies being more severe in patients with ART-induced lipoatrophy. Altered PPARγ expression was reversed in patients stopping PIs. Treatment of patients with agonists of PPARγ could improve, at least partially, the subcutaneous lipoatrophy. These data indicate that decreased PPARγ expression and PPARγ-related function, resulting from ART-induced adipose tissue toxicity, play a central role in HIV-related lipoatrophy and metabolic consequences.

IL-1beta (+3954C/T) polymorphism could protect human immunodeficiency virus (HIV)-infected patients on highly active antiretroviral treatment (HAART) against lipodystrophic syndrome

PURPOSE

To evaluate the impact of acquired and inherited factors on the development of lipodystrophic syndrome in patients on highly active antiretroviral therapy.

METHODS

Two hundred forty-three human immunodeficiency virus-infected Caucasians on highly active antiretroviral therapy were prospectively followed-up for 3 years. Eleven were naIve and 232 were on antiretrovirals (mean, 93.0 months +/- 43.8 months). Lipodystrophic syndrome was diagnosed clinically with a lipodystrophy severity grading scale. Polymorphisms of cytokines (IL-1beta, IL-6, TNF-alpha), TLR4, and NOS genes were genotyped.

RESULTS

Ninety (37%) patients developed lipodystrophic syndrome. The polymorphic T allele of the (+3954C/T) polymorphism of IL-1beta was less frequent in patients with lipodystrophic syndrome compared with those without (17.8% vs. 27.0%, P = 0.03). Factors significantly associated with lipodystrophic syndrome were time on stavudine (P < 0.001), use of stavudine (P = 0.001), absence of the T allele of the (+3954C/T) IL-1beta polymorphism (P = 0.02), acquired immune deficiency syndrome diagnosis (P = 0.005), nadir levels of CD4 (P = 0.003), and time on highly active antiretroviral therapy (P = 0.003). Of these factors, only the time on stavudine (hazard ratio [95% confidence intervals] 1.007 [1.001-1.013]), use of stavudine (1.678 [1.048-2.68]), and absence of the T allele of the IL-1beta (+3954C/T) polymorphism (0.569 [0.347-0.931]) were significantly associated with lipodystrophic syndrome by Cox regression.

CONCLUSIONS

Genotyping of the (+3954C/T) polymorphism of IL-1beta could be useful in patients starting highly active antiretroviral therapy, especially in potential users of stavudine, to predict their risk of developing lipodystrophic syndrome.

Hemochromatosis gene polymorphisms, mitochondrial haplogroups, and peripheral lipoatrophy during antiretroviral therapy

BACKGROUND

Antiretroviral therapy (ART)-associated lipoatrophy involves mitochondrial dysfunction. Iron metabolism impacts mitochondrial function and oxidative stress. Mitochondrial haplogroups and hemochromatosis gene (HFE) polymorphisms have been associated with ART-induced neuropathy. We assessed relationships between these variants and lipoatrophy.

METHODS

The AIDS Clinical Trials Group 384 study randomized ART-naive individuals to receive didanosine-stavudine or zidovudine-lamivudine, combined with efavirenz and/or nelfinavir. Substudy A5005s evaluated fat distribution by dual-energy X-ray absorptiometry (DEXA). We characterized HFE polymorphisms 845G>A and 187C>G and European mitochondrial haplogroups in A5005s participants who consented to genetic analyses.

RESULTS

Among 96 participants (58% were white, and 10% were female) with baseline and 48 or 64 week DEXA data, the median limb fat change was -8.8% (interquartile range, -28.7% to +15.6%). HFE 187C/G heterozygotes (n = 23) had less limb fat loss than 187C/C homozygotes (n = 71) (+6.1% vs. -12.5%; P = .02) and were less likely to develop lipoatrophy after adjustment for age, sex, race, and ART randomization (odds ratio, 0.31; 95% confidence interval, 0.10-0.95; P = .04). Among non-Hispanic white participants, median limb fat change was +26.1% among 5 participants with mitochondrial haplogroup J, compared with -9.7% among 49 participants with other mitochondrial haplogroups (P = .07).

CONCLUSIONS

HFE 187C>G and, possibly, mitochondrial haplogroup J gave relative protection against lipoatrophy during ART in A5005s. These associations should be replicated in other studies.

The IL-6 system in HIV-1-infection and in HAART-related fat redistribution syndromes

We determined the IL-6 -174 G>C single nucleotide polymorphism, IL-6 mRNA expression in subcutaneous adipose tissue (SAT) and IL-6 plasma levels in HIV-1-infected patients with and without lipodystrophy and uninfected controls. HIV-1-infected patients had a greater prevalence of the IL-6 -174 C/C genotype and the C allele, higher SAT IL-6 mRNA expression and plasma IL-6 levels than controls. The IL-6 -174 G>C genotype distribution and allele frequencies, SAT IL-6 mRNA expression and IL-6 plasma levels were non-significantly different between HIV-1-infected patients with and without lipodystrophy.

Human subcutaneous adipose tissue LPIN1 expression in obesity, type 2 diabetes mellitus, and human immunodeficiency virus--associated lipodystrophy syndrome

The aim of this study was to analyze LPIN1 adipose tissue gene expression levels in 3 clinical insulin-resistant conditions-obesity, type 2 diabetes mellitus, and human immunodeficiency virus (HIV)-associated lipodystrophy-and its relationship with adipogenic and inflammatory markers. Subcutaneous adipose tissue samples were obtained from 2 cohorts: 98 subjects with different degrees of adiposity and with or without the presence of type 2 diabetes mellitus and 37 HIV-infected patients. Real-time polymerase chain reaction was used to measure gene expression of LPIN1 and adipogenic (PPARgamma, SREBP1c) and inflammatory markers (IL6, TNFalpha, TNFR1, and TNFR2). LPIN1 messenger RNA expression levels were significantly lower in the obese group (P = .002), were similar in type 2 diabetes mellitus patients and control subjects (P = .211), and were significantly higher in HIV-infected patients (P < .001). LPIN1 messenger RNA levels positively correlated with insulin sensitivity in all subjects. Moreover, an inverse correlation with proinflammatory cytokines was observed.

Lipodystrophy in HIV 1-infected patients: lessons for obesity research

Lipodystrophy is a common alteration in HIV 1-infected patients under anti-retroviral treatment. This syndrome is usually associated with peripheral lipoatrophy, central adiposity and, in some cases, lipomatosis, as well as systemic insulin resistance and hyperlipidemia. Research on the ethiopathogenesis of the disease revealed novel aspects of adipose tissue biology highly relevant to obesity research: the pivotal role of mitochondria in white adipose tissue function, the role that interference with master transcription factors of adipogenesis may have in human adipose tissue, the capacity of human white adipose tissue to acquire brown fat-like features, as well as the importance of apoptosis and the potential impact of viral infections in adipose tissue. The dramatic difference between subcutaneous adipose depots, prone to lipoatrophy, and the visceral adipose depots, prone to enlargement, has been further evidenced in the study of the lipodystrophy syndrome. The recognition of a local pro-inflammatory environment in lipoatrophic adipose tissue from affected patients, including macrophage infiltration and enhanced expression of chemokines and cytokines, points to events paradoxically similar to those in the hypertrophied adipose tissue in obesity. However, this also potentially provides an explanation for the existence of systemic alterations common to lipodystrophy and obese patients and reminiscent of the metabolic syndrome.

Insulin resistance, glucose intolerance and diabetes mellitus in HIV-infected patients

An increased prevalence of insulin resistance, glucose intolerance and diabetes has been reported in HIV infection in the highly active antiretroviral therapy (HAART) era. This development might be clinically significant because of its association with cardiovascular morbidity and mortality as well as the therapeutic challenges of managing polypharmacy. The development of insulin resistance, glucose intolerance and diabetes could be related to the underlying HIV infection, the contribution of different antiretroviral agents, treatment-associated weight gain, immune restoration, as well as the non-HIV related factors. Dissecting these factors in clinical practice might be difficult. Clinical studies include short-term treatments in healthy, non-HIV-infected individuals; randomized, controlled trials; comparative studies of different HAART regimens; and randomized studies of switching regimens in patients with viral suppression and stable immune function. This article reviews the latest knowledge regarding the epidemiology, pathogenesis, prevention and treatment of insulin resistance, glucose intolerance and diabetes mellitus in HIV-infected individuals.

Aging in adipocytes: potential impact of inherent, depot-specific mechanisms

Fat mass and tissue distribution change dramatically throughout life. Fat depot sizes reach a peak by middle or early old age, followed by a substantial decline, together with fat tissue dysfunction and redistribution in advanced old age. These changes are associated with health complications, including type 2 diabetes, atherosclerosis, dyslipidemia, thermal dysregulation, and skin ulcers, particularly in advanced old age. Fat tissue growth occurs through increases in size and number of fat cells. Fat cells turn over throughout the lifespan, with new fat cells developing from preadipocytes, which are of mesenchymal origin. The pool of preadipocytes comprises 15-50% of the cells in fat tissue. Since fat tissue turns over throughout life, characteristics of these cells very likely have a significant impact on fat tissue growth, plasticity, function, and distribution. The aims of this review are to highlight recent findings regarding changes in preadipocyte cell dynamics and function with aging, and to consider how inherent characteristics of these cells potentially contribute to age- and depot-dependent changes in fat tissue development and function.

Patogenia de la lipodistrofia y de las alteraciones metabólicas asociadas a la infección por el VIH

Lipodystrophy, and the metabolic alterations (dislipemia, insulin-resistance) associated with human immunodeficiency virus (HIV) infection, is a multifactorial syndrome due to the interaction of host related factors (cellular immune status, diet, gene mutations), viral factors (cytokine synthesis, polyunsaturated fatty acid or PUFA depletion), and pharmacological effects (mitochondrial DNA-polymerase inhibition, lipolysis inhibition, adiponectin synthesis reduction). HIV probably modifies the adipocyte differentiation and the lipid metabolism. This retroviral effect is mediated by proinflammatory cytokines (tumor necrosis factor) and the participation of other factors (drugs, diet), all in the context of a particular host genetic setting. The adipocyte (and several cellular receptors, fatty acids, membrane proteins, and cytokines) plays a central role in the pathogenesis of HIV-associated lipodystrophy.